I had exactly the same thing, and would come to my senses (for lack of a better term) every so often and be genuinely confused where days or even weeks had gone. One thing that has been really helping me is writing all the little things down such as what I ate or learned in classes as you mentioned.

I personally started using Logseq for this but basically any note taking application will do. The most important feature that I use is linking topics, for example I would mark a bullet point with #food and so on, which eventually organizes the thoughts automatically. It’s really nice to be able to just write and not even think about organizing it as that’s the computer’s job.